1. Field of the Invention
The present invention relates to the mechanical arrangement for interconnecting multiple electrical circuits and more particularly to a mid-plane board for use therein.
2. Description of the Prior Art
A three-dimensional structure for a circuit having a plurality of inputs and outputs is particularly well suited for use in a cross connect network for digital signals transmitted at a high rate, e.g., DS3. The three-dimensional structure provides interconnections which are relatively short and direct as compared to those provided when the inputs and outputs are wired to each other. The relatively short and direct interconnections reduce signal cross talk, attenuation and distortion.
One example of a three-dimensional structure is described in U.S. Pat. No. 4,472,765 (hereinafter the '765 patent). While that structure may become quite complex, in its simplest form it includes a single motherboard and two groups of zero-insertion-force (ZIF) connectors. The two groups of connectors are connected on opposite sides of the motherboard in an orthogonal relationship to each other. Each connector has associated therewith on the motherboard a double row or column of plated through holes. The double row of pins on each ZIF connector are forced into the holes on the board. Only certain pins are used for connecting circuits on a circuit card located on one side of the board to a circuit card located on the other side of the board.
Mounting of the connectors on the motherboard as disclosed in the '765 patent is not desirable. If that board were to be replaced, then it would either be necessary to remove the connectors from the board for use on the new board or have the new board already have such connectors installed thereon. Should the structure be used to interconnect a multiplicity of input and output circuit cards, then such design is wasteful of the connectors. In addition, the structure shown in the '765 patent is not particularly well suited where it is desired to interconnect a multiplicity of input and output lines, each associated with a respective one of the circuit cards to each other. In the structure shown in the '765 patent, each circuit card is also connected to an edge connector for the purposes of making auxiliary connections thereto. Also the structure of the '765 patent requires that there be associated with each card an elongate card guide opposite the ZIF connector associated with the card.
I have found that all of the control signals necessary to perform the desired interconnection between the input and output lines as well as all of the power signals for the input and output circuit cards can be applied directly to the mid-plane board. In addition, I have found that it is not necessary to use elongate card guides in order to bring the cards into contact with the mid-plane board. In the structure of my invention simple slots suffice.